After their launch, telecommunications satellites have to be positioned on their operational orbit—often of geostationary type—and tested in orbit before being able to be handed over to the telecommunications operator who has ordered them after a final in-orbit acceptance review (IOAR).
Conventionally, the method proceeds as follows. First of all, a launcher injects the satellite onto a very elliptical and inclined transfer orbit. The transfer onto geostationary orbit (GEO) is done by chemical propulsion: typically three thrusts each of one hour, over one week. The transfer manoeuvres are generally performed in such a way that the satellite arrives on the GEO orbit at a longitude different from the final longitude, so as not to interfere with the operational satellites—particularly in the case where the satellite to be tested is intended to replace, without any service interruption, a satellite that has to be decommissioned. The in-orbit testing (IOT) is performed in these conditions; they typically last two weeks. Then, the satellite is diverted to reposition it at its final longitude, which takes another few days, even a week or more. In total, a period of between three weeks and more than a month has to be counted between the launch and the IOAR.
By way of example, document WO 2012/040828, which proposes a platform calibration operation before the transfer phase, then an activation and verification of the payload after the satellite has reached its final position.
There is a tendency to replace, wholly or partly, the chemical propulsion of the satellites by electrical propulsion, which has the particular feature of producing a weak thrust (of the order of 1 N or less) with high specific impulse. See for example documents U.S. Pat. No. 5,595,360 and U.S. Pat. No. 8,457,810. The benefit of this approach is that it allows for a significant reduction of the weight of the satellite, and therefore of the launch cost. However, it also leads to a considerable lengthening of the transfer phase, which can take between 3 and 6 months for an entirely electrical propulsion (compared to approximately a week in the case of chemical propulsion), to which approximately another month would have to be added for the IOT and the repositioning on GEO orbit.
Document U.S. Pat. No. 6,341,749 describes a method for stationing a satellite with electrical propulsion, in which the orbital transfer period comprises phases without propulsion which are used to perform earth acquisition and attitude calibration operations, but not payload operations.